January 2015
Volume 56, Issue 1
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Clinical and Epidemiologic Research  |   January 2015
Ocular Higher-Order Wavefront Aberrations in the Japanese Adult Population: the Yamagata Study (Funagata)
Author Affiliations & Notes
  • Hiroyuki Namba
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Ryo Kawasaki
    Department of Public Health, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Mari Narumi
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Akira Sugano
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Kei Homma
    Okitama Public General Hospital, Kawanishi-machi, Yamagata, Japan
  • Katsuhiro Nishi
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Takanori Murakami
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Takeo Kato
    Department of Neurology, Hematology, Metabolism, Endocrinology and Diabetology, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Takamasa Kayama
    Department of Neurosurgery, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Hidetoshi Yamashita
    Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, Yamagata City, Yamagata, Japan
  • Correspondence: Hiroyuki Namba, Department of Ophthalmology and Visual Science, Yamagata University Faculty of Medicine, 2-2-2 Iidanishi, Yamagata City, Yamagata 990-9585, Japan; h-nanba@med.id.yamagata-u.ac.jp
Investigative Ophthalmology & Visual Science January 2015, Vol.56, 90-97. doi:10.1167/iovs.14-15261
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      Hiroyuki Namba, Ryo Kawasaki, Mari Narumi, Akira Sugano, Kei Homma, Katsuhiro Nishi, Takanori Murakami, Takeo Kato, Takamasa Kayama, Hidetoshi Yamashita; Ocular Higher-Order Wavefront Aberrations in the Japanese Adult Population: the Yamagata Study (Funagata). Invest. Ophthalmol. Vis. Sci. 2015;56(1):90-97. doi: 10.1167/iovs.14-15261.

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Abstract

Purpose.: To investigate the relationship between age and ocular higher-order wavefront aberrations (HOAs) in an adult Japanese population, in addition to factors associated with HOA variations.

Methods.: In the Yamagata Study (Funagata) cohort, 227 adult Japanese participants (aged 37–86 years) underwent systemic and ophthalmologic examinations in 2012. Ocular, corneal, and internal HOAs were measured in micrometers. From the Zernike coefficients, we calculated the root mean square of the total HOA, coma, and spherical aberration for a pupil diameter of 4 mm. Linear regression analyses were used to determine whether HOAs were associated with age or other factors.

Results.: Multiple adjusted linear regression analyses demonstrated that all components of logarithmic HOAs increase with age. Ocular, corneal, and internal HOAs increased by 0.012/y (P < 0.001), 0.007/y (P = 0.010), and 0.014/y (P < 0.001), respectively. Ocular coma also significantly increased with age (0.010/y, P = 0.007), but corneal (P = 0.963) and internal (P = 0.476) coma did not. Age-related spherical aberration increased only in the internal component (0.019/y, P = 0.001). In addition to age, ocular and corneal HOAs were mainly affected by corneal indexes.

Conclusions.: Aging is associated with increases in ocular HOAs, independent of other possible confounding factors. The association of ocular HOAs with corneal parameters indicates that ocular HOAs are mainly generated by the cornea. Internal HOAs, supposedly generated from cataract progression, may be associated with systemic factors, including serum creatinine levels and blood pressure.

Introduction
Human vision quality is influenced by ocular aberrations in the eye, which, in combination with other optical factors (e.g., intraocular scattering), degrade images projected onto the retina.1,2 Ocular aberrations may originate from the inherent shape of the corneal surface, corneal refractive index, alignment of optical components, or intraocular conditions including those related to the crystalline lens. Wavefront sensing enables the measurement of irregular astigmatism as higher-order wavefront aberrations (HOAs), beyond defocus and regular astigmatism.37 A wavefront aberration is defined as an optical deviation along a certain ray from the perfect spherical wavefront. Zernike polynomials have been widely used to characterize and evaluate wavefront aberrations of the human eye.8 Correlations of Zernike polynomials with contrast sensitivity9,10 and best-corrected visual acuity (BCVA)11 have been reported. 
It has also been reported that aging affects the amount of HOAs that produce optical deterioration.1221 Aberrations on the anterior surface of the cornea and in the internal optics of the crystalline lens can cancel each other out,22 particularly in young subjects. Artal et al.23 showed that aging disrupts this balance between corneal and internal lens aberrations. A better understanding of the causes of optical deterioration within the aging eye will improve the maintenance of vision quality in the elderly. 
Although HOAs have been the topic of many recent studies, the major HOA determinants are still not fully understood. We conducted this study as a part of the Yamagata Study (Funagata), a population-based study of adult Japanese subjects, to investigate age-related changes in ocular, corneal, and internal HOAs. Although HOAs have been previously investigated in hospital-based studies, to the best of our knowledge, a population-based study has not yet been conducted. In addition to age-related changes, we investigated other factors that may influence HOAs. 
Methods
Subjects
The present study was performed as a part of the Yamagata Study (Funagata), a population-based epidemiologic study examining systemic and ophthalmologic disorders in Japanese individuals aged 35 years and older. Details regarding the study participants and research methodology have been previously described.2429 Briefly, systemic and ophthalmic data were obtained from residents living in Funagata town via study examinations in June 2012. Informed consent was obtained from all study participants, and study conduct adhered to the tenets of the Declaration of Helsinki. The Yamagata Study (Funagata) was approved by the Ethics Committee of the Yamagata University Faculty of Medicine, Yamagata, Japan. 
Wavefront aberration and corneal topographic data from only the right eye were used to avoid the use of interdependent data between two eyes from the same subject. As previously reported, aberrations were relatively similar in the left and right eyes of a given subject.1,3,16 Patients were excluded from the current analyses if they had a history of ocular or corneal surgery, corneal scarring, or other corneal pathology (e.g., pterygium) on slit-lamp examination. Subjects with missing or insufficient data were also excluded. 
Examination
Wavefront aberration and corneal topographic data were obtained using the Hartmann-Shack wavefront analyzer and the corneal topographer, both contained within one apparatus (KR-1W; Topcon Corp., Tokyo, Japan). Ocular and corneal HOA values were determined, and based on these values, internal HOA values (mainly generated by the lens) were calculated. All HOA measurements were taken in a semidark room without the use of dilating agents and were repeated at least three times. Although previous studies showed that dry eye affects the instability of higher-order aberrations,30,31 measurement repetition may partly reduce its influence. Average ocular, corneal, and internal aberrations in the central 4 mm of measurement were quantitatively analyzed. Using the Zernike coefficients, we calculated each root mean square (RMS, in micrometers) of the total HOA (tHOA), coma (square root of the sum of the squared coefficients of Z3−1, Z31, Z5−1, and Z51), vertical coma (square root of the sum of the squared coefficients of Z3−1 and Z5−1), horizontal coma (square root of the sum of the squared coefficients of Z31 and Z51), and spherical aberration (SA, square root of the sum of the squared coefficients of Z40 and Z60) of the ocular, corneal, and internal components. 
Refractive spherical and cylindrical error, corneal spherical and cylindrical power, and intraocular pressure were measured using an auto ref/kerato/tonometer (TONOREF II; NIDEK CO., LTD., Aichi, Japan). Axial length (AxL) and central corneal thickness (CCT) were measured by partial coherence laser interferometry (OA-1000; TOMEY Corp., Aichi, Japan). Best-corrected visual acuity was measured at a distance of 4 meters in a bright room using the tumbling E Eye chart in the Early Treatment Diabetic Retinopathy Study (ETDRS) format fitted to the standardized ETDRS viewers. Body indexes, such as height, weight, and waist size, were measured while subjects were wearing light clothing and no shoes. Blood pressure measurements and serologic tests were also used in the current analyses. 
Statistical Analyses
Data were analyzed using SPSS statistical software (SPSS Statistics version 21.0; IBM Corp., Armonk, NY, USA). In simple and multiple regression analysis models, statistical significance was defined as P < 0.05. The natural logarithmic transformation (base e) was used in linear regression analyses to approximate HOA data to a normal distribution. Data points determined to be significant outliers in logarithmic values by the Smirnov-Grubbs test (only this test was performed using Ekuseru-Toukei 2012 [Social Survey Research Information Co., Ltd., Tokyo, Japan]) were removed from analyses. The outliers for ocular aberration were as follows: two subjects in tHOA, four in coma, one in horizontal coma, and three in SA. Corneal aberration had four outliers in tHOA and three in coma. Internal aberration had four outliers in tHOA, five in coma, two in vertical coma, three in horizontal coma, and four in SA. 
Associations among age, BCVA, and HOAs were examined using simple and multiple adjusted linear regression analyses. Variables associated with both age and each type of HOA were included in multiple regression models as potential confounding factors. Age- and sex-adjusted stepwise regression analyses were also used to identify other factors associated with HOAs. 
Results
Subject Characteristics
Table 1 summarizes the characteristics of the 227 subjects (111 male [49%], 116 female [51%]) included in the current analyses. The age range of the subjects was 37 to 86 (63.07 ± 11.17) years. 
Table 1
 
Demographic Characteristics
Table 1
 
Demographic Characteristics
Mean Standard Deviation
Age, y 63.07 11.17
Sex, male/female 111/116
Height, cm 158.95 9.32
Weight, kg 60.82 11.73
BMI, kg/m2 23.93 3.07
IOP, mm Hg 14.21 2.57
Axial length, mm 23.58 1.21
CCT, μm 517.14 27.70
Corneal power, D 43.84 1.52
Refractive power, D* 0.32 2.62
Corneal cylinder, D† 0.81 0.74
Refractive cylinder, D† 0.94 0.76
Association Between Higher-Order Wavefront Aberrations and Best-Corrected Visual Acuity
The associations between HOAs and BCVA are summarized in Table 2. Ocular (P < 0.001), corneal (P = 0.003), and internal (P < 0.001) tHOA increases were all associated with deterioration of BCVA. Corneal tHOA was not associated with BCVA in an age-adjusted linear regression analysis (P = 0.085). 
Table 2
 
Impact of HOAs on logMAR BCVA
Table 2
 
Impact of HOAs on logMAR BCVA
Independent Variables Linear Regression Analysis Age-Adjusted Linear Regression Analysis
Regression Coefficient 95% CI P Value Regression Coefficient 95% CI P Value
Ocular
 Total HOA 0.421 0.224, 0.617 0.000 0.294 0.091, 0.497 0.005
 Coma 0.259 0.016, 0.501 0.037 0.181 −0.057, 0.418 0.136
 Vertical coma 0.235 0.013, 0.456 0.038 0.204 −0.009, 0.418 0.060
 Horizontal coma 0.242 −0.035, 0.519 0.086 0.080 −0.197, 0.357 0.570
 SA 0.559 0.225, 0.893 0.001 0.444 0.116, 0.773 0.008
Corneal
 Total HOA 0.382 0.130, 0.634 0.003 0.226 −0.031, 0.483 0.085
 Coma 0.028 −0.302, 0.357 0.869 −0.008 −0.324, 0.307 0.959
 Vertical coma 0.078 −0.191, 0.348 0.566 0.066 −0.192, 0.323 0.616
 Horizontal coma 0.085 −0.360, 0.529 0.707 −0.076 −0.505, 0.353 0.728
 SA −0.238 −0.878, 0.402 0.465 −0.180 −0.788, 0.428 0.560
Internal
 Total HOA 0.490 0.277, 0.704 0.000 0.353 0.129, 0.577 0.002
 Coma 0.223 −0.079, 0.526 0.147 0.112 −0.186, 0.409 0.460
 Vertical coma 0.195 0.025, 0.365 0.025 0.144 −0.021, 0.310 0.086
 Horizontal coma 0.266 0.005, 0.527 0.046 0.136 −0.123, 0.395 0.301
 SA 0.408 −0.026, 0.842 0.065 0.196 −0.240, 0.631 0.377
Age-Related Change in Higher-Order Wavefront Aberrations
An overview of age-related changes in ocular, corneal, and internal HOAs is given in the Figure. The results of the linear regression analyses are summarized in Table 3. Logarithmic tHOAs increased in the ocular, corneal, and internal components with increasing age (all P < 0.001). Ocular coma was also significantly affected by age (P = 0.003), but corneal (P = 0.119) and internal (P = 0.055) coma were not. Horizontal coma and SA increased with age in the ocular (P < 0.001 and P = 0.014, respectively) and internal (P = 0.001 and P < 0.001, respectively) components, but not in the corneal component (P = 0.074 and P = 0.841, respectively). Absolute values in actual numbers calculated from the results of linear regression analyses at specified ages are also included in Table 3
Figure.
 
Scatterplots indicating associations of age and higher-order aberrations (HOAs). Age-related changes of ocular (AC), corneal (GI), and internal (MO) HOAs are expressed as the root mean square (RMS). Age-related changes of ocular (DF), corneal (JL), and internal (PR) logarithmic HOAs are also expressed, and regression lines are drawn when the regression analyses are statistically significant (total HOA, coma, and SA in ocular component; total HOA in corneal component; and total HOA and SA in internal component).
Figure.
 
Scatterplots indicating associations of age and higher-order aberrations (HOAs). Age-related changes of ocular (AC), corneal (GI), and internal (MO) HOAs are expressed as the root mean square (RMS). Age-related changes of ocular (DF), corneal (JL), and internal (PR) logarithmic HOAs are also expressed, and regression lines are drawn when the regression analyses are statistically significant (total HOA, coma, and SA in ocular component; total HOA in corneal component; and total HOA and SA in internal component).
Table 3
 
Evaluation of Age-Related Changes Using Linear Regression Analysis
Table 3
 
Evaluation of Age-Related Changes Using Linear Regression Analysis
Dependent Variables Linear Regression Analysis, Logarithm Absolute Values of HOA RMSs Expressed in Micrometers, Actual Number Multiple Adjusted Linear Regression Analysis,* Logarithm
Starting Value Change per Y of Age 95% CI P Value 40 Y Old 50 Y Old 60 Y Old 70 Y Old 80 Y Old Change per Y of Age 95% CI P Value
Ocular
 Total HOA −2.705 0.014 0.009, 0.018 0.000 0.116 0.133 0.152 0.175 0.200 0.012 0.006, 0.018 0.000
 Coma −3.155 0.012 0.004, 0.019 0.003 0.068 0.076 0.085 0.096 0.107 0.010 0.003, 0.018 0.007
 Vertical coma −3.521 0.010 −0.001, 0.022 0.080 0.045 0.049 0.055 0.061 0.067 0.008 −0.004, 0.019 0.189
 Horizontal coma −4.950 0.028 0.018, 0.039 0.000 0.022 0.029 0.039 0.052 0.068 0.024 0.010, 0.038 0.001
 SA −3.865 0.012 0.003, 0.022 0.014 0.035 0.039 0.044 0.050 0.057 0.003 −0.008, 0.013 0.664
Corneal
 Total HOA −2.489 0.010 0.006, 0.014 0.000 0.122 0.135 0.149 0.164 0.181 0.007 0.002, 0.012 0.010
 Coma −2.883 0.005 −0.001, 0.012 0.119 0.069 0.073 0.077 0.081 0.085 0.000 −0.007, 0.007 0.963
 Vertical coma −3.482 0.006 −0.005, 0.018 0.295 0.039 0.042 0.045 0.048 0.051 0.007 −0.004, 0.019 0.228
 Horizontal coma −3.766 0.009 −0.001, 0.018 0.074 0.033 0.036 0.039 0.043 0.046 0.000 −0.012, 0.012 0.998
 SA −3.149 −0.001 −0.009, 0.007 0.841 0.042 0.041 0.041 0.041 0.040 −0.003 −0.011, 0.005 0.485
Internal
 Total HOA −3.092 0.016 0.011, 0.021 0.000 0.087 0.102 0.120 0.141 0.166 0.014 0.007, 0.020 0.000
 Coma −3.125 0.007 0.000, 0.015 0.055 0.059 0.064 0.069 0.074 0.079 0.003 −0.005, 0.011 0.476
 Vertical coma −3.693 0.009 −0.002, 0.020 0.119 0.035 0.039 0.042 0.046 0.051 0.001 −0.011, 0.014 0.823
 Horizontal coma −4.312 0.017 0.007, 0.026 0.001 0.026 0.031 0.037 0.043 0.051 0.014 0.004, 0.025 0.008
 SA −4.651 0.023 0.012, 0.033 0.000 0.024 0.030 0.038 0.047 0.059 0.019 0.008, 0.031 0.001
Multiple linear regression modeling revealed a mean increase in logarithmic tHOAs in the ocular (P < 0.001), corneal (P = 0.010), and internal (P < 0.001) components for every year of age. These associations were independent of possible confounding factors. Horizontal coma increased with age in the ocular (P = 0.001) and internal (P = 0.008) components. An age-related SA increase was observed only in the internal component (P = 0.001). 
Factors Other Than Age Associated With Higher-Order Wavefront Aberrations
Ophthalmologic and systemic factors other than age associated with HOAs are described in Table 4. Similar to corneal HOAs, ocular HOAs were associated with corneal indexes, including corneal power, CCT, and corneal cylinder. Additionally, corneal HOAs were associated with some physical factors, and internal HOAs were not associated with corneal indexes. Serum creatinine and blood pressure were associated with internal HOAs. Therefore, internal horizontal coma and SA had no significant associations other than age. 
Table 4
 
Associations Other Than Age
Table 4
 
Associations Other Than Age
Dependent Variable Age- and Sex-Adjusted Linear Regression Analysis
Independent Variable Regression Coefficient Standardizing Coefficient 95.0% CI P Value
Ocular
 Log, total HOA Corneal power 0.042 0.153 0.008, 0.076 0.015
CCT 0.002 0.140 0.000, 0.004 0.026
Waist size 0.006 0.128 0.000, 0.012 0.043
 Log, coma CCT 0.004 0.180 0.001, 0.007 0.008
Corneal power 0.072 0.166 0.015, 0.129 0.014
 Log, vertical coma Corneal power 0.165 0.255 0.081, 0.249 0.000
Corneal cylinder* 0.211 0.157 0.041, 0.380 0.015
CCT 0.006 0.156 0.001, 0.010 0.019
 Log, horizontal coma None
 Log, SA Corneal cylinder* 0.179 0.158 0.034, 0.324 0.016
Corneal
 Log, total HOA Corneal power 0.047 0.201 0.018, 0.077 0.002
Corneal cylinder* 0.097 0.195 0.036, 0.159 0.002
CCT 0.002 0.150 0.000, 0.004 0.019
 Log, coma AxL −0.117 −0.251 −0.186, −0.049 0.001
Weight 0.010 0.204 0.002, 0.018 0.019
 Log, vertical coma CCT 0.140 0.214 0.055, 0.224 0.001
Corneal power 0.007 0.188 0.002, 0.012 0.005
Serum LDL cholesterol 0.005 0.140 0.000, 0.010 0.034
 Log, horizontal coma Waist size 0.017 0.183 0.005, 0.029 0.008
 Log, SA CCT −0.004 −0.183 −0.008, −0.001 0.007
Internal
 Log, total HOA Corneal cylinder* 0.091 0.152 0.019, 0.163 0.013
Serum creatinine 0.523 0.192 0.102, 0.945 0.015
 Log, coma Systolic blood pressure 0.007 0.161 0.000, 0.013 0.036
 Log, vertical coma Serum creatinine 1.241 0.212 0.259, 2.222 0.013
Diastolic blood pressure 0.015 0.135 0.000, 0.030 0.046
 Log, horizontal coma None
 Log, SA None
Discussion
Consistent with the findings of previous studies,1,2,9,10,14 the present study shows that HOA increase is associated with deterioration of visual function in the ocular, corneal, and internal components. The present age-adjusted linear regression analysis (corneal tHOA was not associated with BCVA) suggests that corneal HOAs are more sensitive to increasing age than internal HOAs. 
We carefully considered age and other potentially related factors to elucidate the association between age and HOAs. Multiple adjusted linear regression analyses revealed that ocular, corneal, and internal tHOAs all increase with age, independent of potential confounding factors including AxL, patient height, corneal power, and systolic blood pressure. Although the age ranges of the subjects differ among studies, our results are consistent with those of previous studies.1216,19 
The correlation of HOAs with age remains somewhat controversial. Fujikado et al.18 reported that corneal tHOA was not significantly correlated with age. This discrepancy relative to our study may have resulted from differing definitions of tHOA between the studies, because the previous study included only third- and fourth-order aberrations. Berrio et al.20 reported that internal tHOA was not correlated with age. Because of the small study population and the bimodal distribution of the subjects in the previous study, collection bias may have been unavoidable. We found that ocular coma was positively associated with age, while corneal and internal coma were not. We consider that this difference may arise from the change in compensation between the corneal and internal coma with age. The compensation of internal optics to corneal vertical and horizontal coma has been shown to be negatively correlated with age.20 Therefore, if corneal and internal coma did not increase independently, ocular coma would increase as a result of the change in relationship between corneal and internal coma from compensation to summation. This finding is consistent with the results of Fujikado et al.18 Other studies have shown a correlation of corneal coma with age,13,16,17 but our study did not. This discrepancy may have resulted from differences in pupil size between our subjects and those of the other studies. Our data were collected from a central 4-mm area, but those reported in other studies were mostly collected from a 6- or 7-mm area. We also found that both ocular and internal horizontal coma, but not corneal horizontal coma, increased with age, which was consistent with the findings of Berrio et al.20 Simple linear regression showed an age-related SA increase in the ocular component; however, this change was not observed upon multiple adjusted linear regression analysis. Although previous studies have demonstrated a significant increase in ocular SA with age,17,18,20 those studies may have been affected by significant confounding factors, including body height and weight. 
We present HOA absolute values at specific ages in Table 3. The ocular tHOA RMS was 0.116 μm at 40 years of age and 0.200 μm at 80 years of age. Considering our results shown in Table 2, generational HOA differences between the ages of 40 and 80 years may have resulted in the observed +0.354 in logMAR BCVA. 
Fujikado et al.18 reported larger HOAs than our study because they included other constituents of third- or fourth-order aberrations. Our absolute values are similar to the ocular HOA results reported by Applegate et al.19 and corneal coma reported by Guirao et al.,21 suggesting a lack of difference between Japanese and Caucasian aberrations. However, the HOA RMS reported by Berrio et al.20 was typically larger than that reported in our study. Thus, ethnic differences should still be considered. 
The association of ocular HOAs with corneal parameters strongly suggests that increases in ocular HOAs are mainly determined by changes in corneal condition. In contrast, internal HOAs are rarely associated with corneal indexes, suggesting that internal aberrations mainly originate in the crystalline lens. Only internal tHOA was associated with corneal cylinder, indicating that the posterior corneal surface may generate a small HOA. Interestingly, we found that serum creatinine and blood pressure were associated with internal HOAs, which agrees with previous reports showing that cataract progression is associated with serum creatinine and blood pressure.3235 
Our study had several strengths not present in previous reports. Our study population was relatively large, with 227 subjects included. In addition, previous reports were mainly hospital based, whereas our study was population based. Moreover, other studies utilizing correlation analyses may not have considered potential confounding factors. As a part of the Yamagata Study (Funagata), we collected detailed systemic and ophthalmic data and used multiple regression models to investigate factors associated with ocular, corneal, and internal HOAs. 
Our study also had several limitations. First, when comparing our findings with those of earlier studies, we were able only to estimate whether or not our results for age-related HOA changes conflicted with previous results because HOAs in earlier studies were defined and estimated in various ways. Second, HOA increases in the elderly do not directly indicate visual deterioration because the reduction of pupil size with age compensates for the HOA increase, as some previous studies have indicated.1214,19 Third, our HOA data were collected from the central 4 mm of a natural pupil (without mydriasis), and pupil diameter is known to affect HOAs.1,4,5,1214,19 Although a larger pupil diameter is generally preferable for evaluation of optical characteristics, we consider that the pupils of our subjects were sufficiently large for evaluating practical visual function; other studies have also adopted a 4-mm diameter for the pupil.1,5,12,18,32 Fourth, factors potentially associated with HOAs may not have been measured, including factors excluded from serologic tests, sleeping habits, or occupation. Sleeping habits may affect eyelid/cornea contact, and it is known that the eyelid influences corneal shape.36,37 Some subjects may have had occupational exposure to ultraviolet or radiation, which is known to advance cataract maturation.32,38 Lastly, this analysis was based on cross-sectional data obtained in 2012 as a part of the Yamagata Study (Funagata), a longitudinal cohort study. Therefore, age-related changes in HOAs were not evaluated in individuals over time. Further studies with a wide range of data collected over an extended period of time are needed to evaluate age-related trends in HOAs over time. 
In conclusion, ocular HOAs, including the corneal and internal components, increase with age. The present study demonstrates that in addition to age, most ocular HOAs are generated by the cornea. Additionally, internal HOAs are associated with systemic indexes, suggesting that HOAs increase with cataract progression. 
Acknowledgments
Disclosure: H. Namba, None; R. Kawasaki, None; M. Narumi, None; A. Sugano, None; K. Homma, None; K. Nishi, None; T. Murakami, None; T. Kato, None; T. Kayama, None; H. Yamashita, P 
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Figure.
 
Scatterplots indicating associations of age and higher-order aberrations (HOAs). Age-related changes of ocular (AC), corneal (GI), and internal (MO) HOAs are expressed as the root mean square (RMS). Age-related changes of ocular (DF), corneal (JL), and internal (PR) logarithmic HOAs are also expressed, and regression lines are drawn when the regression analyses are statistically significant (total HOA, coma, and SA in ocular component; total HOA in corneal component; and total HOA and SA in internal component).
Figure.
 
Scatterplots indicating associations of age and higher-order aberrations (HOAs). Age-related changes of ocular (AC), corneal (GI), and internal (MO) HOAs are expressed as the root mean square (RMS). Age-related changes of ocular (DF), corneal (JL), and internal (PR) logarithmic HOAs are also expressed, and regression lines are drawn when the regression analyses are statistically significant (total HOA, coma, and SA in ocular component; total HOA in corneal component; and total HOA and SA in internal component).
Table 1
 
Demographic Characteristics
Table 1
 
Demographic Characteristics
Mean Standard Deviation
Age, y 63.07 11.17
Sex, male/female 111/116
Height, cm 158.95 9.32
Weight, kg 60.82 11.73
BMI, kg/m2 23.93 3.07
IOP, mm Hg 14.21 2.57
Axial length, mm 23.58 1.21
CCT, μm 517.14 27.70
Corneal power, D 43.84 1.52
Refractive power, D* 0.32 2.62
Corneal cylinder, D† 0.81 0.74
Refractive cylinder, D† 0.94 0.76
Table 2
 
Impact of HOAs on logMAR BCVA
Table 2
 
Impact of HOAs on logMAR BCVA
Independent Variables Linear Regression Analysis Age-Adjusted Linear Regression Analysis
Regression Coefficient 95% CI P Value Regression Coefficient 95% CI P Value
Ocular
 Total HOA 0.421 0.224, 0.617 0.000 0.294 0.091, 0.497 0.005
 Coma 0.259 0.016, 0.501 0.037 0.181 −0.057, 0.418 0.136
 Vertical coma 0.235 0.013, 0.456 0.038 0.204 −0.009, 0.418 0.060
 Horizontal coma 0.242 −0.035, 0.519 0.086 0.080 −0.197, 0.357 0.570
 SA 0.559 0.225, 0.893 0.001 0.444 0.116, 0.773 0.008
Corneal
 Total HOA 0.382 0.130, 0.634 0.003 0.226 −0.031, 0.483 0.085
 Coma 0.028 −0.302, 0.357 0.869 −0.008 −0.324, 0.307 0.959
 Vertical coma 0.078 −0.191, 0.348 0.566 0.066 −0.192, 0.323 0.616
 Horizontal coma 0.085 −0.360, 0.529 0.707 −0.076 −0.505, 0.353 0.728
 SA −0.238 −0.878, 0.402 0.465 −0.180 −0.788, 0.428 0.560
Internal
 Total HOA 0.490 0.277, 0.704 0.000 0.353 0.129, 0.577 0.002
 Coma 0.223 −0.079, 0.526 0.147 0.112 −0.186, 0.409 0.460
 Vertical coma 0.195 0.025, 0.365 0.025 0.144 −0.021, 0.310 0.086
 Horizontal coma 0.266 0.005, 0.527 0.046 0.136 −0.123, 0.395 0.301
 SA 0.408 −0.026, 0.842 0.065 0.196 −0.240, 0.631 0.377
Table 3
 
Evaluation of Age-Related Changes Using Linear Regression Analysis
Table 3
 
Evaluation of Age-Related Changes Using Linear Regression Analysis
Dependent Variables Linear Regression Analysis, Logarithm Absolute Values of HOA RMSs Expressed in Micrometers, Actual Number Multiple Adjusted Linear Regression Analysis,* Logarithm
Starting Value Change per Y of Age 95% CI P Value 40 Y Old 50 Y Old 60 Y Old 70 Y Old 80 Y Old Change per Y of Age 95% CI P Value
Ocular
 Total HOA −2.705 0.014 0.009, 0.018 0.000 0.116 0.133 0.152 0.175 0.200 0.012 0.006, 0.018 0.000
 Coma −3.155 0.012 0.004, 0.019 0.003 0.068 0.076 0.085 0.096 0.107 0.010 0.003, 0.018 0.007
 Vertical coma −3.521 0.010 −0.001, 0.022 0.080 0.045 0.049 0.055 0.061 0.067 0.008 −0.004, 0.019 0.189
 Horizontal coma −4.950 0.028 0.018, 0.039 0.000 0.022 0.029 0.039 0.052 0.068 0.024 0.010, 0.038 0.001
 SA −3.865 0.012 0.003, 0.022 0.014 0.035 0.039 0.044 0.050 0.057 0.003 −0.008, 0.013 0.664
Corneal
 Total HOA −2.489 0.010 0.006, 0.014 0.000 0.122 0.135 0.149 0.164 0.181 0.007 0.002, 0.012 0.010
 Coma −2.883 0.005 −0.001, 0.012 0.119 0.069 0.073 0.077 0.081 0.085 0.000 −0.007, 0.007 0.963
 Vertical coma −3.482 0.006 −0.005, 0.018 0.295 0.039 0.042 0.045 0.048 0.051 0.007 −0.004, 0.019 0.228
 Horizontal coma −3.766 0.009 −0.001, 0.018 0.074 0.033 0.036 0.039 0.043 0.046 0.000 −0.012, 0.012 0.998
 SA −3.149 −0.001 −0.009, 0.007 0.841 0.042 0.041 0.041 0.041 0.040 −0.003 −0.011, 0.005 0.485
Internal
 Total HOA −3.092 0.016 0.011, 0.021 0.000 0.087 0.102 0.120 0.141 0.166 0.014 0.007, 0.020 0.000
 Coma −3.125 0.007 0.000, 0.015 0.055 0.059 0.064 0.069 0.074 0.079 0.003 −0.005, 0.011 0.476
 Vertical coma −3.693 0.009 −0.002, 0.020 0.119 0.035 0.039 0.042 0.046 0.051 0.001 −0.011, 0.014 0.823
 Horizontal coma −4.312 0.017 0.007, 0.026 0.001 0.026 0.031 0.037 0.043 0.051 0.014 0.004, 0.025 0.008
 SA −4.651 0.023 0.012, 0.033 0.000 0.024 0.030 0.038 0.047 0.059 0.019 0.008, 0.031 0.001
Table 4
 
Associations Other Than Age
Table 4
 
Associations Other Than Age
Dependent Variable Age- and Sex-Adjusted Linear Regression Analysis
Independent Variable Regression Coefficient Standardizing Coefficient 95.0% CI P Value
Ocular
 Log, total HOA Corneal power 0.042 0.153 0.008, 0.076 0.015
CCT 0.002 0.140 0.000, 0.004 0.026
Waist size 0.006 0.128 0.000, 0.012 0.043
 Log, coma CCT 0.004 0.180 0.001, 0.007 0.008
Corneal power 0.072 0.166 0.015, 0.129 0.014
 Log, vertical coma Corneal power 0.165 0.255 0.081, 0.249 0.000
Corneal cylinder* 0.211 0.157 0.041, 0.380 0.015
CCT 0.006 0.156 0.001, 0.010 0.019
 Log, horizontal coma None
 Log, SA Corneal cylinder* 0.179 0.158 0.034, 0.324 0.016
Corneal
 Log, total HOA Corneal power 0.047 0.201 0.018, 0.077 0.002
Corneal cylinder* 0.097 0.195 0.036, 0.159 0.002
CCT 0.002 0.150 0.000, 0.004 0.019
 Log, coma AxL −0.117 −0.251 −0.186, −0.049 0.001
Weight 0.010 0.204 0.002, 0.018 0.019
 Log, vertical coma CCT 0.140 0.214 0.055, 0.224 0.001
Corneal power 0.007 0.188 0.002, 0.012 0.005
Serum LDL cholesterol 0.005 0.140 0.000, 0.010 0.034
 Log, horizontal coma Waist size 0.017 0.183 0.005, 0.029 0.008
 Log, SA CCT −0.004 −0.183 −0.008, −0.001 0.007
Internal
 Log, total HOA Corneal cylinder* 0.091 0.152 0.019, 0.163 0.013
Serum creatinine 0.523 0.192 0.102, 0.945 0.015
 Log, coma Systolic blood pressure 0.007 0.161 0.000, 0.013 0.036
 Log, vertical coma Serum creatinine 1.241 0.212 0.259, 2.222 0.013
Diastolic blood pressure 0.015 0.135 0.000, 0.030 0.046
 Log, horizontal coma None
 Log, SA None
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